1. Field of the Invention
The present invention relates to an electronic musical instrument which utilizes a system for assigning newly depressed key data to a selected one of all musical tone generating channels when they are being assigned with previously depressed key data and which is further provided with an envelope generator for producing an envelope through phase splitting.
2. Description of the Prior Art
Heretofore there has been proposed an electronic musical instrument which is equipped with an assignor system by which when the number of keys depressed at a time is greater than the number of musical tone generating channels, data of the most recently depressed key is assigned to any one of the channels so as to create an intended musical tone. Such an electronic musical instrument is designed so that where a new key depression occurs when all the channels are being assigned with data of previously depressed keys, truncate processing is conducted by which (I) the assignment of data of that one of the depressed keys which was released earlier than any others is terminated and the newly depressed key data is assigned to that channel, or (II) where all the channels are being assigned with data of keys still depressed, the assignment of data of that one of the depressed keys which was depressed earlier than any others is terminated and the newly depressed key data is assigned to that channel.
In the case (I), however, (A) an attack envelope of the tone of the newly assigned key (hereinafter referred to simply as a new tone) rises before a release envelope of the tone of the previously assigned key (hereinafter referred to simply as a previous tone) is completely finished as shown in FIG. 10A, with the result that no sufficient feeling of attack can be created for the new tone. (B) A solution to this problem, suggested so far, is a method by which when the new tone is developed, the release envelope of the previous tone is immediately cleared to the zero level to permit the attack envelope of the new tone to rise up from the zero level to thereby produce the new tone with a satisfactory feeling of attack. However, this method is not preferable in that a click is generated when the release envelope of the previous tone is cleared to the zero level. Further, there have been suggested two methods (C) and (D) shown in FIG. 10B, but these methods also encounter the same problems as mentioned above.
To obviate the above-mentioned defect of the method (B) in the case (I), it has been proposed to decay or release the envelope of the previous tone at high speed instead of clearing it. In the prior art, however, only one kind of parameter data for such high-speed release is prepared for one electronic musical instrument, and hence is always used no matter what timbre is selected. It is evident, however, it is preferable, for faithful tone reproduction, to set optimum parameter data for each timbre selected.
Moreover, the conventional electronic musical instrument performs the high-speed release in a channel in which the key previously assigned to the channel has been released; in the afore-mentioned case (II), the high-speed release takes place after forcibly releasing the previously assigned key. This will inevitably increase the number of programs used, complicate them, and increase the processing time involved in the case of employing an assignor including a microcomputer or the like, and introduce complexity in the circuit arrangement in the case of using an assignor formed by logic hardware.